1. Field of the Invention
The present invention relates to an electronic musical instrument which plays a melody which is stored in advance in accordance with an operation of, e.g., a keyboard.
2. Description of the Related Art
A conventional electronic musical instrument normally has a so-called one-key play mode (e.g., U.S. Pat. Nos. 4,022,097 and 4,448,104, and Published Examined Japanese Patent Application No. 62-32791). In an electronic musical instrument of this type, a special key called a one-key is arranged at a position separated from a keyboard. When the one-key is depressed in correspondence with a rhythm, a predetermined melody stored in, e.g., a ROM pack automatically progresses. According to a musical instrument of this type, a beginner can easily play various melodies in correct rhythm.
In the one-key play mode, a user only depresses a key called the one-key in place of key depression operations on the keyboard. Therefore, the user cannot experience that he or she actually plays a keyboard, resulting in dissatisfaction.
For this reason, in some musical instruments, all the keys on the keyboard are regarded as the one-keys, and a melody progresses every time an arbitrary key on the keyboard is depressed (e.g., U.S. Pat. Nos. 4,476,766, 4,361,076, 4,594,931, and 4,522,100).
However, the keys on the keyboard are arranged adjacent to each other without gaps. For this reason, a beginner tends to erroneously depress a plurality of keys at the same time. In this case, melody tones progress by the number of depressed keys not to be synchronized with rhythm. Recently, electronic musical instruments tend to be utilized as early music education tools or toys for infants. However, it is difficult for infants to precisely depress keys one by one, and they tend to simultaneously tap a plurality of keys with their fists or palms. For this reason, in order to assist infants to learn a rhythmical sense of a melody, an auto play function which recognizes a simultaneous depression of a plurality of keys as an operation of one key, and plays a melody is preferable. In this case, it is also preferable for an electronic musical instrument that a performance using both hands can be performed like in acoustic keyboards such as a piano, an organ, a cembalo, and the like.